
public class recurtionDemmmmo {

	static double pow2(int n){
		if(n == 0)
			return 1;
		if (n < 0)
			return 1 / pow2(-n);
		return 2 * pow2(n-1);
	}

	public static void main(String[] args) {

System.out.println(pow2(5));
	}

}
